In the refining of crude oil and the manufacture of chemicals the formation of iron sulfide often presents operational and maintenance problems. Accumulation of iron sulfide deposits can accumulate in heat exchangers, reactor beds, tower trays and other process equipment. Such accumulations decrease efficiency and eventually require taking the equipment out of service for removal of the deposits.
Products such as poly(isobutenyl) succinimides are known as 20 dispersants for hydrogen sulfide in process streams. These products, unlike the present invention, contains nitrogen which acts as a catalyst poison in some operations. In addition, higher concentrations of the products are required to disperse iron sulfide than are required with the instant invention.
Polymers comprising .alpha.-olefins and maleic anhydride are well known. Rossi U.S. Pat. No. 4,240,916 discloses an oil soluble copolymer composed of about equimolar amounts of 1-olefins and maleic anhydride useful as a lubricating oil pour point depressant wherein the 1-olefins are a mixture of C.sub.10 -C.sub.14 and C.sub.20 -C.sub.28 monomers. The pour point depressant activity is said to be enhanced by esterification of the copolymer with a C.sub.1 -C.sub.4 alcohol.
Rossi U.S. Pat. No. 4,151,069 discloses olefin dicarboxylic anhydride copolymers and their ester derivatives having C.sub.18 -C.sub.50 linear alkyl side chains. The polymers and derivatives are said to be useful in amounts of up to 5 weight percent as filtration aids in low temperature solvent dewaxing of waxy lubricating oils containing 5-30 weight percent wax.
Similarly, U.S. Pat. No. 3,694,176 to Miller, discloses polymers of ethylene and ethylenically unsaturated dicarboxylic acids, anhydrides or esters as wax crystal modifiers, pour point depressants and dewaxing aids in petroleum oil.
Rossi U.S. patent application Ser. No. 515,562, filed Oct. 17, 1974, abandoned, discloses that partial alkyl ester-partial amide derivatives of low molecular weight maleic anhydride/1-olefin copolymers are useful in mineral oil lubricants as pour point depressants, viscosity index improvers and sludge inhibitors.
Japanese Kokai 62-018,494 discloses low temperature flow improvers for fuel oils which are copolymers of a C.sub.20 -C.sub.28 .alpha.-olefins and maleic anhydride.
U.S. Pat. No. 3,560,456 to Hazan et al. discloses a process for making a copolymer of maleic anhydride and an aliphatic olefin having from 16-18 carbon atoms in the presence of a free radical catalyst and a solvent. The copolymer is precipitated from solution using n-propanol or isopropanol.
U.S. Pat. No. 3,231,458 to de Vries discloses a high molecular weight copolymer of .alpha.-olefins of from about 2 to about 20 carbon atoms and diolefins of from about 5 to about 20 carbon atoms reacted with maleic anhydride to form a succinic anhydride-substituted adduct said to have rust inhibiting, dispersing and thickening characteristics in liquid hydrocarbon compositions, such as fuels and lubricants.
U.S. Pat. No. 4,919,683 to Nalesnik, et al. discloses a stabilizer for a middle distillate fuel-oil which is an aromatic polyamine succinimide derivative of an ethylene/C.sub.3 -C.sub.18 .alpha.-olefin copolymer grafted with maleic anhydride.
U.S. Pat. No. 4,866,135 to Gutierrez et al. discloses a reaction product of a C.sub.5 -C.sub.9 lactone adduct of a maleic anhydride grafted ethylene/C.sub.3 -C.sub.28 .alpha.-olefin polymer with an N-containing heterocyclic aminoalkyl derivative. The polymeric lactone derivatives are said to be useful as dispersant additive for fuel and lubricating oils.
U.S. Pat. No. 4,548,725 to Bridger discloses a lubricant additive said to reduce low temperature microcrystalline wax formation in hydro-dewaxed stock made by reacting an alcohol with a maleic anhydride-olefin copolymer.
U.S. Pat. No. 3,531,440 to Mehmedbasich et al. discloses succinate ester modified polymers of C.sub.6 -C.sub.18 .alpha.-olefins employed as H dispersants in fuels.